1. Field of the Invention
The present invention relates to an apparatus for connecting and disconnecting a clutch, and more particularly to such a connection/disconnection apparatus which can automatize operations of a vehicle's clutch.
2. Description of the Related Art
Recently in an automobile industry, there is known an automatic speed change (or transmission) system which includes a clutch disconnection/connection unit for automatically disconnecting and connecting a friction clutch, an automatic transmission unit associated with a manual transmission for automatically changing a shift position of the manual transmission, and an engine control unit for regulating an engine. This automatic speed change system executes clutch disconnection/connection control, speed change (shift position change) control and engine control when a vehicle driver wants to change a shift position.
In general, the automatic speed change system controls the clutch and engine such that the friction clutch slips as small as possible during clutch connection when the driver shifts the shift lever. On the other hand, if a vehicle is not equipped with the automatic speed change system (or in the case of common manual operation vehicle), a driver stamps down an acceleration pedal while maintaining a clutch pedal in a half connected position during clutch connection, so that the friction clutch slips to a certain extent while the engine is accelerated until the clutch connection and shift position change are completed. Therefore, when a vehicle equipped with the conventional automatic speed change system is compared with a common manual operation vehicle, the driver of the vehicle equipped with the automatic speed change system feels somehow strange in the clutch half connected condition when the driver intends to speed up the vehicle. This is because the clutch connection proceeds slowly and the driver feels tardiness during engine speed acceleration.
In order to eliminate this drawback, the clutch connection control to the automatic speed change system should be performed such that the clutch is allowed to slip to a certain extent in the half connected condition. However, this control may admit overslippage. A measure to prevent overslipping of the friction clutch is then required.
Japanese Utility Model Application, Kokai No. 61-69550 discloses a technique that regulates an engine speed to be close to a clutch disc rotating speed before clutch connection is carried out. The clutch connection is performed when the rotational speed difference between the engine and clutch is reduced to a particular range. This softens a shock caused upon clutch connection.